An increasing number of mobile devices support one or more voice activation (VA) features. Often these VA features include the mobile device receiving a custom key word spoken by the user, where the mobile device then performs certain operations depending on the content of the keyword, e.g. wake up the device from sleep mode, launch an application, or make a phone call. However, the VA features must be running wherever and whenever the user wishes to issue a voice command, and the VA features thus constantly consume power. Furthermore, when the microphone of the device is concealed in a bag, pocket, purse, case, or belt holster, the poor voice quality is challenging for VA to work properly. Moreover, the rubbing of the pocket/bag/purse material creates noise, which may cause false triggering of VA and thus waste the limited power available to the mobile device.